Grafting of Poly [(2-Diethylamino)Ethyl Methacrylate] onto Chitosan

In this study, chitosan was grafted with poly[(2-diethyl amino)ethyl methacrylate] in homogeneous and heterogeneous systems by using potassium persulphate as the initiator. The effect of temperature, time, (2-diethyl amino)ethyl methacrylate concentration and the concentration of the initiator on the grafting yield was examined in aqueous acetic solution under nitrogen atmosphere. The maximum grafting percentage of poly[(2-diethyl amino)ethyl methacrylate] on to chitosan was found to be 180% under homogeneous conditions using 0.5 mL of monomer concentration with 1.00 g chitosan dissolved in 1.0mL of 0.10% (w/v) acetic acid solution, temperature at 70◦C and 4 hour reaction time. The products were precipitated in ethanol in the powder form. They were found to be water soluble which is an improvement over the dissolution properties of the parent molecule, namely chitosan. Chitosan tripolyphosphate gel beads which were chemically crosslinked by glutaraldehyde or ethylene glycol digylcidyl ether were used as solid substrates for grafting of poly[(2-diethyl amino)ethyl methacrylate] PDEAEM in a heterogeneous system at the optimum conditions determined for the homogeneous system. The maximum grafting yield was found to be in the range 40-50%. The swelling kinetics of the grafted beads was followed in acidic, neutral and basic buffer solutions. The experiments demonstrated 166-4811% swelling within 72 hours. The synthesized copolymers were characterized by using Fourier Transform Infrared spectroscopy (FTIR), thermo gravimetric analysis (TGA), and scanning electron microscopy (SEM). Keywords: graft copolymerization, natural polymer, chitosan, chitosan tripolyphosphate bead, (2-diethyl amino)ethyl methacrylate (DEAEM), water soluble polymer.